Pharmaceutical composition for and method of treating leukemia

ABSTRACT

Method of treating leukemia, inhibiting the growth or proliferation of leukemic cells or extending the life span of a animal having leukemia are disclosed. The methods comprise the step of treating the leukemia with an effective amount of a compound of the Formula I  
                 
 
     or a pharmaceutically acceptable salt or prodrug form thereof, wherein:  
     X is hydrogen, halogen or alkyl of less than 7 carbon atoms;  
     n is a positive integer of less than 4;  
     Y is hydrogen, chlorine, nitro, methyl or ethyl;  
     R is hydrogen or an alkyl group of from 1 to 8 carbon atoms, alkylcarbamyl;  
     R 2  is 4-thiazolyl or NHCOOR 1 ; and  
     R 1  is an aliphatic hydrocarbon of less than 7 carbon atoms.  
     A chemotherapeutic agent and/or potentiator can be used in conjunction with the compound of the Formula I.

[0001] This is a continuation in part application of application Ser.No. 08/910,801 filed Aug. 12, 1997, which is a continuation ofapplication Ser. No. 08/473,817 filed on Jun. 7, 1995.

TECHNICAL FIELD

[0002] This invention relates to a pharmaceutical composition for and amethod of treating leukemia in mammals, wherein the compositioncomprises a benzimidazole derivative.

BACKGROUND OF THE INVENTION

[0003] Cancers, including leukemia, are the leading cause of death inanimals and humans. The exact cause of many cancers is not known, butlinks between certain activities such as smoking or exposure tocarcinogens and the incidence of certain types of carcinomas, lymphomas,e.g., leukemia and tumors, has been shown by a number of researchers.

[0004] Many types of chemotherapeutic agents have been shown to beeffective against leukemia, but not all types of leukemia cells respondto these agents, and, unfortunately, many of these agents also destroynormal cells.

[0005] Despite advances in the field of leukemia treatments, the leadingtherapies to date are radiation, chemotherapy and bone marrowtransplants. However, these therapies generally harm normal cells aswell as leukemic cells. Ideally cytotoxic agents that have specificityfor leukemia cells while only minimally affecting normal healthy cellswould be extremely desirable. Unfortunately, none have been found andinstead agents which target especially rapidly dividing cells (bothdiseased and normal) have been used.

SUMMARY OF THE INVENTION

[0006] The invention provides a method, and pharmaceutical compositiontherefor, of treating leukemia, inhibiting the growth or inhibiting theproliferation of leukemic cells while affecting little or no undesiredside effects on normal cells, and extending the life span of a animalhaving leukemia. Accordingly, one aspect of the invention provides amethod of treating leukemia in a animal comprising the step ofadministering to the animal a safe and effective amount of a compound ofthe Formula:

[0007] or a pharmaceutically acceptable salt or prodrug form thereof,wherein:

[0008] X is hydrogen, halogen, alkyl of less than 7 carbon atoms oralkoxy of less than 7 carbon atoms;

[0009] n is a positive integer of less than 4;

[0010] Y is hydrogen, chlorine, nitro, methyl or ethyl;

[0011] R is hydrogen or an alkyl group of from 1 to 8 carbon atoms; oralkylcarbamoyl wherein the alkyl group has from 3 to 6 carbon atoms;

[0012] R₂ is 4-thiazolyl or NHCOOR₁; and

[0013] R₁ is an aliphatic hydrocarbon of less than 7 carbon atoms; and apharmaceutically acceptable carrier.

[0014] Preferably the compositions are:

[0015] wherein R is an alkyl of 1 through 8 carbon atoms and R₂ isselected from the group consisting of 4-thiazolyl, NHCOOR₁, wherein R₁is methyl, ethyl or isopropyl and the non-toxic, pharmaceuticallyacceptable acid addition salts with both organic and inorganic acids orprodrugs thereof.

[0016] R₁ is preferably an alkyl group of less than 7 carbon atoms. Inother preferred embodiments, R is an alkyl of from 1 to 8 carbon atomsand R₁ is methyl, ethyl or isopropyl. The most preferred compoundsinclude those wherein Y is chloro and X is hydrogen and also2-(4-thiazolyl)benzimidazole (thiabendazole),methyl(butylcarbamoyl)-2-benzimidazolecarbamate (benomyl) and2-(methoxycarbonylamino)benzimidzole (carbendazim).

[0017] The compound of the Formula I is used alone or in combinationwith a potentiator or other chemotherapeutic agent to treat leukemia.

[0018] Another aspect of the invention provides a method of inhibitingthe proliferation of leukemic cells in vitro, in vivo or ex vivocomprising the step of treating said cells with an effective amount ofthe compound of the Formula I, as defined above. Optionally, one or morepotentiators and chemotherapeutic agents are used in combination withthe compound of the Formula I to inhibit the proliferation of leukemiccells.

[0019] Yet another aspect of the invention provides a method ofinhibiting the growth of leukemic cells in vitro, in vivo or ex vivocomprising the step of treating said cells with an effective amount ofthe compound of the Formula I, as defined above. Optionally, one or morepotentiators and chemotherapeutic agents are used in combination withthe compound of the Formula I to inhibit the growth of leukemic cells.

[0020] Still another aspect of the invention provides a method ofextending the life span of a animal having leukemia comprising the stepof administering to the animal an effective amount of the compound ofthe Formula I, as defined above, whereby the life span of the animal isextended beyond the expected life span of a comparable animal having acomparable degree of leukemia development not being treated with acompound of the Formula I. Optionally, one or more potentiators andchemotherapeutic agents are used in combination with the compound of theFormula I to extend the life span of the animal.

[0021] A further aspect of the invention provides a pharmaceuticalcomposition for the treatment of leukemia in a animal comprising apharmaceutically acceptable carrier, an effective amount of a compoundof the Formula I, as defined above, and a safe and effective amount ofone or more potentiators and other chemotherapeutic agents.

[0022] The pharmaceutical composition of the invention includes allknown stereoisomers, enantiomers, regioisomers, stereoisomers, anddiastereomers of the compound of the Formula I as well aspharmaceutically acceptable salts and prodrugs thereof.

[0023] The compounds of the invention are administered orally, rectally,topically, intravenously, or parenterally.

DETAILED DESCRIPTION OF THE INVENTION

[0024] A. DEFINITIONS

[0025] As used herein, “Formula I” refers to a benzimidazole having thegeneral formula:

[0026] or a pharmaceutically acceptable salt or prodrug form thereof,wherein:

[0027] X is hydrogen, halogen, alkyl of less than 7 carbon atoms oralkoxy of less than 7 carbon atoms;

[0028] n is a positive integer of less than 4;

[0029] Y is hydrogen, chlorine, nitro, methyl or ethyl;

[0030] R is hydrogen or an alkyl group of from 1 to 8 carbon atoms; oralkylcarbamoyl wherein the alkyl group has from 3 to 6 carbon atoms;

[0031] R₂ is 4-thiazolyl or NHCOOR₁; and

[0032] R₁ is an aliphatic hydrocarbon of less than 7 carbon atoms

[0033] As used herein, a “pharmaceutically acceptable” component is onethat is suitable for use with humans and/or animals without undueadverse side effects (such as toxicity, irritation, and allergicresponse) commensurate with a reasonable benefit/risk ratio. It isexpected, however, that some side effects may be observed duringtreatment with a compound of the Formula I.

[0034] As used herein, the term “animal” includes any warm bloodedanimal and the preferred animals are mammals.

[0035] As used herein, the term “safe and effective amount” or“therapeutically effective amounts” refers to the quantity of acomponent which is sufficient to yield a desired therapeutic responsewithout undue adverse side effects (such as toxicity, irritation, orallergic response) commensurate with a reasonable benefit/risk ratiowhen used in the manner of this invention. The specific “safe andeffective amount” will vary with such factors as the particularcondition being treated, the physical condition of the patient, the typeof animal being treated, the duration of the treatment, the nature ofconcurrent therapy (if any), and the specific formulations employed andthe structure of the compounds or its derivatives.

[0036] As used herein, the term “prodrug” refers to a form of thecompound of the Formula I that has minimal therapeutic activity until itis converted to its desired biologically active form. A prodrug is acompound having one or more functional groups or carriers covalentlybound thereto which functional groups or carriers are removed from thecompound to form the biologically active form. A prodrug of a compoundof the Formula I is prepared by modifying one or more functional groupspresent in the compound with one or more masking groups in such a waythat the masking groups are cleaved, either in vivo after administrationor in vitro prior to administration to form the biologically activeform. Prodrugs include compounds wherein one or more of the functionalgroups of the compound of the Formula I are bonded to one or moreprotecting groups that cleave to form the unprotected or derivatizedcompound of the Formula I. Exemplary protecting groups are disclosed in“Protective Groups in Organic Synthesis” (by Green & Wuts, 1999, 3^(rd)Ed.); “Protecting Groups (Tieme Foundations Organic Chemistry Series NGroup” (by Kocienskie; Tieme Medical Publishers; 1994), the relevantdisclosures of which are hereby incorporated by reference.

[0037] “Prodrugs” are considered to be any covalently bonded carrierswhich release the active parent drug according to the formula of thebenzimidazole derivatives described above in vivo when such prodrug isadministered to a animalian subject. Prodrugs of the benzimidazolecompounds are prepared by modifying functional groups present in thecompounds in such a way that the modifications are cleaved, either inroutine manipulation or in vivo, to the parent compounds. Prodrugsinclude compounds wherein hydroxy, amine, or sulfhydryl groups arebonded to any group that, when administered to a mammalian subject,cleaves to form a free hydroxyl, amino, or sulfhydryl grouprespectively. Examples of prodrugs include, but are not limited to,acetate, formate, or benzoate derivatives of alcohol and aminefunctional groups in the benzimidazole derivatives; phosphate esters,dimethylglycine esters, aminoalkylbenzyl esters, aminoalkyl esters andcarboxyalkyl esters of alcohol and phenol functional groups in thebenzimidazole derivatives; and the like.

[0038] As used herein, a “pharmaceutical carrier” is a pharmaceuticallyacceptable solvent, suspending agent or vehicle for delivering thecompound of the Formula I to an animal or human. The carrier may beliquid or solid and is selected with the planned manner ofadministration in mind.

[0039] As used herein, “cancer” or “leukemia” refers to neoplasticdiseases which attack normal healthy blood cells, or bone marrow whichproduces blood cells, which are found in animals. The term “leukemia”refers broadly to progressive, malignant diseases of the blood-formingorgans and is generally characterized by a distorted proliferation anddevelopment of leukocytes and their precursors in the blood and bonemarrow. Leukemia is generally clinically classified on the basis of (1)the duration and character of the disease, i.e., acute or chronic; (2)the type of cell involved; myeloid (myelogenous), lymphoid(lymphogenous), or monocytic; and (3) the increase or non-increase inthe number abnormal cells in the blood-leukemic or aleukemic(subleukemic).

[0040] The P388 leukemia model described herein is widely accepted asbeing predictive of in vivo anti-leukemia activity. It is believed thatcompound that tests positive in the P388 assay will generally exhibitsome level of anti-leukemia activity in vitro, ex vivo or in vivo. Thelevel of anti-leukemia activity will depend upon the type of leukemiabeing treated. Accordingly, the present invention includes methods oftreating leukemia, inhibiting the proliferation of leukemic cells,inhibiting the growth of leukemic cells or extending the life span of aanimal having leukemia where the leukemia is selected from the groupincluding acute nonlymphocytic leukemia, chronic lymphocytic leukemia,acute granulocytic leukemia, chronic granulocytic leukemia, acutepromyelocytic leukemia, adult T-cell leukemia, aleukemic leukemia, aleukocythemic leukemia, basophylic leukemia, blast cell leukemia, bovineleukemia, chronic myelocytic leukemia, leukemia cutis, embryonalleukemia, eosinophilic leukemia. Gross leukemia, hairy-cell leukemia,hemoblastic leukemia, hemocytoblastic leukemia, histiocytic leukemia,stem cell leukemia, acute monocytic leukemia, leukopenic leukemia,lymphatic leukemia. lymphoblastic leukemia, lymphocytic leukemia,lymphogenous leukemia, lymphoid leukemia, lymphosarcoma cell leukemia,mast cell leukemia, megakaryocrytic leukemia, micromyeloblasticleukemia, monocytic leukemia, myeloblastic leukemia, myelocyticleukemia, myeloid granulocytic leukemia, myelomonocytic leukemia,Naegeli leukemia, plasma cell leukemia, plasmacytic leukemia,promyelocytic leukemia, Rieder cell leukemia, Schilling's leukemia, stemcell leukemia, subleukemic leukemia, and undifferentiated cell leukemia.

[0041] As used herein, the term “susceptible to treatment” refers to aleukemia which can be treated with a compound of the Formula I accordingto the methods of the invention. For example, leukemia which issusceptible to treatment will respond favorably to chemotherapy with acompound of the Formula I. A favorable response would includeprolongation of the life span of a animal having the leukemia,inhibition of the proliferation of leukemic cells, inhibition of agrowth of leukemic cells, reduction in the rate of disease progressionin the animal, remission or regression of the disease in the animal,and/or improvement in the quality of life of a animal having leukemia. Aleukemia can be identified as being susceptible to treatment byfollowing the method of example 3 described below.

[0042] The compounds of the Formula I are prepared according to themethod described in U.S. Pat. No. 3,738,995 issued to Adams et al., Jun.12, 1973. The thiazolyl derivatives are prepared according to the methoddescribed in Brown et al. (J. Am. Chem. Soc. (1961), 83, 1764), andGrenda et al. (J. Org. Chem. (1965), 30, 259). Some of these compoundsare also commercially available from BASF, Hoechst, E. I. Du Pont deNemours, and MSD-AgVet. One skilled in the art of organic synthesis caneasily determine methods to make the compounds of Formula I.

[0043] B. ADJUNCT THERAPY

[0044] As used herein, “adjunct therapy” means that the patient in needof the drug is treated or given another drug for the disease and/or apotentiator in conjunction with the compound of the Formula I. Thisadjunct therapy can be sequential therapy where the patient is treatedfirst with one compound and then the other within a given time period orconcommitant therapy where the two compounds are administeredsubstantially simultaneously or in overlapping dosing regimens.

[0045] The compound of the Formula I generally is used in single ormultiple treatments. Alternatively, the compound of the Formula I iscombined with other therapeutic agents, chemotherapeutic agents orpotentiators to treat disorders. “Potentiators” are materials whichaffect the body's response or diseased cell's response to the compoundof the Formula I. A “potentiator” can be any material which improves orincreases the efficacy of a pharmaceutical composition containing thecompound of the Formula I or acts as an immunomodulator to increase theefficacy of the compound of the Formula I.

[0046] In some embodiments of the invention, the compound of the FormulaI is used in combination with one or more other anti-inflammatory,anti-viral, anti-fungal, amoebicidal, trichomonocidal, analgesic,anti-neoplastic, anti-hypertensives, anti-microbial and/or steroid drugsto treat leukemia and optionally another ongoing disease or disorder. Anexemplary potentiator is triprolidine or its cis-isomer which are usedin combination with chemotherapeutic agents and a compound of theFormula I. Triprolidine is described in U.S. Pat. No. 5,114,951 (1992).Another potentiator is procodazole, 1H-Benzimidazole-2-propanoic acid;[β-(2-benzimidazole) propionic acid; 2-(2-carboxyethyl)benzimidazole;propazol]. Procodazole is a non-specific immunoprotective agent activeagainst viral and bacterial infections that is used with thecompositions claimed herein. It is effective with a compound of theFormula I in the methods of the invention. Procodazole can also becombined with a compound of the Formula I and other chemotherapeuticagents and used in the method of the invention.

[0047] Other potentiators which can be used with a compound of theFormula I, and optionally another chemotherapeutic agent, in the methodsof the invention include macrophage colony-stimulating factor (M-CSF),7-thia-8-oxoguanosine, 6-mercaptopurine, vitamin A (retinol), and otherknown anti-tumor potentiators which can be used in conjunction with thecompounds of Formula I include, monensin, an anti-sense inhibitor of theRAD51 gene, bromodeoxyuridine, dipyridamole, indomethacin, a monoclonalantibody, an anti-transferrin receptor immunotoxin, metoclopramide,N-solanesyl-N,N′-bis(3,4-dimethoxybenzyl)ethylenediamine, leucovorin,heparin, N-[4-[(4-fluorphenyl)sulfonly]phenyl] acetamide, heparinsulfate, cimetidine, a radiosensitizer, a chemosensitizer, a hypoxiccell cytotoxic agent, muramyl dipeptide, vitamin A, 2′-deoxycoformycin,a bis-diketopiperazine derivative, and dimethyl sulfoxide otheranti-tumor potentiators.

[0048] The chemotherapeutic agents which can be used with a compound ofthe Formula I and an optional potentiator are generally grouped asDNA-interactive Agents, Antimetabolites, Tubulin-Interactive Agents,Hormonal agents and others such as Asparaginase or hydroxyarea. Each ofthe groups of chemotherapeutic agents can be further divided by type ofactivity or compound. For a detailed discussion of chemotherapeuticagents and their method of administration, see Dorr, et al, CancerChemotherapy Handbook, 2d edition, pages 15-34, Appleton & Lange(Connecticut, 1994) the disclosure of which is hereby incorporated byreference.

[0049] DNA-Interactive Agents include the alkylating agents, e.g.Cisplatin, Cyclophosphamide, Altretamine; the DNA strand-breakageagents, such as Bleomycin; the intercalating topoisomerase IIinhibitors, e.g., Dactinomycin and Doxorubicin); the nonintercalatingtopoisomerase II inhibitors such as, Etoposide and Teniposde; and theDNA minor groove binder Plcamydin.

[0050] The alkylating agents form covalent chemical adducts withcellular DNA, RNA, and protein molecules and with smaller amino acids,glutathione and similar chemicals. Generally, these alkylating agentsreact with a nucleophilic atom in a cellular constituent, such as anamino, carboxyl, phosphate, sulfhydryl group in nucleic acids, proteins,amino acids, or glutathione. The mechanism and the role of thesealkylating agents in cancer therapy is not well understood. Typicalalkylating agents include:

[0051] Nitrogen mustards, such as Chlorambucil, Cyclophosphamide,Isofamide, Mechlorethamine, Melphalan, Uracil mustard;

[0052] Aziridine such as Thiotepa;

[0053] methanesulphonate esters such as Busulfan;

[0054] nitroso ureas, such as Carmustine, Lomustine, Streptozocin;

[0055] platinum complexes, such as Cisplatin, Carboplatin;

[0056] bioreductive alkylator, such as Mitomycin, and Procarbazine.Dacarbazine and Altretamine.

[0057] DNA strand breaking agents include Bleomycin.

[0058] DNA topoisomerase II inhibitors include the following:

[0059] Intercalators, such as Amsacrine, Dactinomycin, Daunorubicin,Doxorubicin, Idarubicin, and Mitoxantrone; and

[0060] nonintercalators, such as Etoposide and Teniposide.

[0061] The DNA minor groove binder is Plicamycin.

[0062] The antimetabolites interfere with the production of nucleicacids by one or the other of two major mechanisms. Some of the drugsinhibit production of the deoxyribonucleoside triphosphates that are theimmediate precursors for DNA synthesis, thus inhibiting DNA replication.Some of the compounds are sufficiently like purines or pyrimidines to beable to substitute for them in the anabolic nucleotide pathways. Theseanalogs can then be substituted into the DNA and RNA instead of theirnormal counterparts. The antimetabolites useful herein include:

[0063] folate antagonists such as Methotrexate and trimetrexate

[0064] pyrimidine antagonists, such as Fluorouracil,Fluorodeoxyunridine, CB3717, Azacitidine and Floxuridine

[0065] purine antagonists such as Mercaptopurine, 6-Thioguanine,Pentostatin;

[0066] sugar modified analogs such as Cytarabine and Fludarabine; and

[0067] ribonucleotide reductase inhibitors such as hydroxyurea.

[0068] Tubulin Interactive agents act by binding to specific sites ontubulin, a protein that polymerizes to form cellular microtubules.Microtubules are critical cell structure units. When the interactiveagents bind on the protein, the cell can not form microtubules TubulinInteractive agents include colchicine, Vincristine and Vinblastine, bothalkaloids and Paclitaxel and cytoxan.

[0069] Hormonal agents are also useful in the treatment of cancers andtumors. They are used in hormonally susceptible tumors and are usuallyderived from natural sources These include:

[0070] estrogens, conjugated estrogens and Ethinyl Estradiol andDiethylstilbesterol. Chlortrianisen and Idenestrol;

[0071] progestins such as Hydroxyprogesterone caproate.Medroxyprogesterone, and Megestrol; and

[0072] androgens such as testosterone, testosterone propionate;fluoxymesterone. methyltestosterone.

[0073] Adrenal corticosteroids are derived from natural adrenal cortisolor hydrocortisone. They are used because of their anti inflammatorybenefits as well as the ability of some to inhibit mitotic divisions andto halt DNA synthesis. These compounds include, Prednisone,Dexamethasone, Methylprednisolone, and Prednisolone.

[0074] Leutinizing hormone releasing hormone agents orgonadotropin-releasing hormone antagonists are used primarily thetreatment of prostate cancer. These include leuprolide acetate andgoserelin acetate. They prevent the biosynthesis of steroids in thetestes.

[0075] Antihormonal antigens include:

[0076] antiestrogenic agents such as Tamoxifen,

[0077] antiandrogen agents such as Flutamide; and

[0078] antiadrenal agents such as Mitotane and Aminoglutethimide.

[0079] Hydroxyurea, which appears to act primarily through inhibition ofthe enzyme ribonucleotide reductase, can also be used in combinationwith the compound of the Formula I.

[0080] Asparaginase is an enzyme which converts asparagine tononfunctional aspartic acid and thus blocks protein synthesis in thetumor. Asparaginase can also be used in combination with the compound ofthe Formula I to treat cancer.

[0081] Other chemotherapeutic benzimidazoles and griseofulvin can alsobe used in combination with the compound of the Formula I and optionallya potentiator to treat or inhibit the growth of cancer or extend thelife span of a animal having cancer.

[0082] The amount and identity of a chemotherapeutic agent that is usedwith a compound of the Formula I in the methods of the invention willvary according to cellular response, patient response and physiology,type and severity of side effects, the disease being treated, thepreferred dosing regimen, patient prognosis or other such factors.

[0083] The compound of the Formula I can be used in combination with oneor more other agents or combination of agents known to possessanti-leukemia activity including, by way of example, α-interferon;interleukin-2; cytarabine and mitoxantrone; cytarabine and daunorubicinand 6-thioguanine; cyclophosphamide and 2-chloro-2′-deoxyadenosine;VP-16 and cytarabine and idorubicin or mitoxantrone; fludarabine andcytarabine and γ-CSF; chlorambucil; cyclophosphamide and vincristine and(prednisolone or prednisone) and optionally doxorubicin; tyrosine kinaseinhibitor; an antibody; glutamine; clofibric acid; all-trans retinoicacid; ginseng diyne analog; KRN8602 (anthracycline drug); temozolomideand poly(ADP-ribose) polymerase inhibitors; lysofylline; cytosinearabinoside; chlythorax and elemental enteral diet enriched withmedium-chain triglycerides; amifostine; gilvusmycin; or a hot waterextract of the bark of Acer nikoense.

[0084] The compound of the Formula I can also be used in combinationwith other non-chemotherapeutic treatments for leukemia including bonemarrow transplant, therapeutic apheresis, and radiation.

[0085] When a compound of the Formula I is used in combination withother therapeutic agents, the ratio of the compound of the Formula I tothe other therapeutic agent will be varied as needed according to thedesired therapeutic effect, the observed side-effects of thecombination, or other such considerations known to those of ordinaryskill in the medical arts. Generally, the ratio of the compound of theFormula I to other therapeutic agent will range from about 0.5%:99.5%wt. to about 99.5%:0.5% wt. Preferably from 1%:99% wt. to about 50%:50%wt. When the compound of the Formula I is administered before or afterother therapeutic agents to treat viral infections, cancer, tumors, orother diseases, the respective doses and the dosing regimen of thecompound of the Formula I and the other therapeutic agent may vary. Theadjunct therapy can be sequential, that is the treatment with one agentfirst and then the second agent, or it can be concomitant treatmentwherein two or more agents are administered substantially at the sametime. The sequential therapy can be within a reasonable time after thecompletion of the first therapy before beginning the second therapy. Thetreatment with both agents at the same time can be in the same dailydose or in separate doses. For example treatment with one agent on day 1and the other on day 2. The exact regimen will depend on the diseasebeing treated, the severity of the infection and the response to thetreatment.

[0086] For example, a full dosing regimen of the compound of the FormulaI can be administered either before or after a full dosing regimen ofthe other therapeutic agent, or alternating doses of the compound of theFormula I and the other therapeutic agent may be administered. As afurther example, the compound of the Formula I can be administeredconcomitantly with the other therapeutic agent.

[0087] Propionic acid and its salts and esters can also be used incombination with the pharmaceutical compositions claimed herein.Antioxidant vitamins such as vitamins A, C and E and beta-carotene canbe added to these compositions.

[0088] C. DOSAGE AND DELIVERY FORMS

[0089] Any suitable dosage may be given in the method of the invention.The type of compound and the carrier and the amount will vary widelydepending on the species of the warm blooded mammal, body weight, or thetype of leukemia being treated. Generally a dosage of between about 2milligram (mg) per kilogram (kg) of body weight and about 10000 mg perkg of body weight is suitable for the compound of the Formula I.Preferably from 150 mg to about 8000 mg/kg of body weight is used.

[0090] A dosage unit may comprise a single compound or mixtures thereofwith other compounds or other cancer inhibiting compounds. The dosageunit can also comprise diluents, extenders, carriers, liposomes and thelike. The unit may be in solid or gel form such as pills, tablets,capsules and the like or in liquid form suitable for oral, rectal,topical, intravenous injection or parenteral administration or injectioninto or around the bone marrow.

[0091] The dosage for the chemotherapeutic agent can be from about 1 mgto about 1000 mg/kg and will be the same as or less than the dosagenormally used for that agent.

[0092] The range and ratio of the compound of the Formula I tochemotherapeutic agent will depend on the type of cancer or tumor beingtreated and the particular chemotherapeutic agent. Generally the rangeof dosage for the chemotherapeutic agent will the same as or lower thanthat used when the chemotherapeutic agent is used alone. The ratio ofthe compound of the Formula I to the chemotherapeutic agent willgenerally be in the range of about 1000:1 to 10:1, and preferably in therange of about 800:1 to 100:1 on a weight basis. Generally, about 500 mgto 5000 mg of the compound of the Formula I/kg of body weight isadministered when about 0.5 to about 40 mg of the chemotherapeutic/kg ofbody weight is administered.

[0093] Any range of doses can be used. Generally the compound of theFormula I can be administered on a daily basis one or more times a day,or the compound of the Formula I can be given once to four times a weekeither in a single dose or separate doses during the day. Twice weeklydosing over a period of several weeks is preferred. However, the dosageand the dosage regimen will vary depending on the ability of the patientto sustain the desired and effective plasma levels of the the compoundof the Formula I in the blood.

[0094] The identity of the chemotherapeutic agent, the pharmaceuticalcarrier and the amount of compound administered will vary widelydepending on the species and body weight of mammal and the type ofleukemia being treated. The dosage administered will vary depending uponknown factors, such as the pharmacodynamic characteristics of a specificchemotherapeutic agent and its mode and route of administration; theage, sex, metabolic rate, absorptive efficiency, health and weight ofthe recipient; the nature and extent of the symptoms; the kind ofconcurrent treatment being administered; the frequency of treatmentwith; and the desired therapeutic effect.

[0095] The compound of the Formula I, the potentiator and thechemotherapeutic agent are administered together in a single dosage formor separately in two or more different dosage forms. These can beadministered independently by the same route or by two or more differentroutes of administration depending on the dosage forms employed.

[0096] The compound of the Formula I is preferably micronized orpowdered so that it is more easily dispersed and solubilized by thebody. Processes for grinding or pulverizing drugs are well known in theart. For example, a hammer mill or similar milling device are used.

[0097] Dosage forms (compositions) suitable for internal administrationcontain from about 1.0 milligram to about 5000 milligrams of activeingredient per unit. In these pharmaceutical compositions, the activeingredient will ordinarily be present in an amount of about 0.5 to about95% by weight based on the total weight of the composition. Based on thebody weight of the patient, the dosage may be administered in one ormore doses several times per day or per week. Multiple dosage units maybe required to achieve a therapeutically effective amount. For example,if the dosage form is 1000 mg, and the patient weighs 40 kg, one pillwill provide a dose of 25 mg per kg for that patient. It will provide adose of only 12.5 mg/kg for a 80 kg patient.

[0098] The compound of the Formula I has exhibited efficacy in vivoagainst leukemia in mice at doses of about 1000, 2000 and 4000mg/kg.Generally, an effective dose in mice is about 12 times the expectedeffective dose in humans. By way of general guidance, for humans adosage of as little as about 2 milligrams (mg) per kilogram (kg) of bodyweight and up to about 10,000 mg per kg of body weight is suitable as atherapeutically effective dose. Preferably, from about 150 mg/kg toabout 5,000 250 mg/kg of body weight is used. Other preferred dosesrange between 100 mg/kg to about 3000 mg/kg of body weight. However, adosage of between about 2 milligrams (mg) per kilogram (kg) of bodyweight to about 400 mg per kg of body weight is also suitable fortreating some forms of leukemia.

[0099] Suitable pharmaceutical compositions and dosage forms willpreferably comprise the compound of the Formula I, a potentiator andoptionally a chemotherapeutic agent. The ratio of the compound of theFormula I to potentiator is generally in the range of about 1000:1 to1:1, and preferably 500:1 to 10:1 on a weight basis. When achemotherapeutic agent is also present, the ratio of the compound of theFormula I to potentiator to chemotherapeutic agent is generally in therange of about 1000:1:1 to about 1:1:1, and preferably 500:1: to about300:100.

[0100] Generally about 2 to 1000 mg of the compound of the Formula I perkg of body weight is administered when about 2 to 500 mg ofpotentiator/kg of body weight and about 0.5 to 100 mg ofchemotherapeutic agent/kg of body weight are administered.

[0101] Intravenously, the most preferred rates of administration mayrange from about 1 to about 1000 mg/kg/minute during a constant rateinfusion. The compound of the Formula I may be administered in a singledaily dose, or the total daily dosage may be administered in divideddoses of two, three, or four times daily. The compound of the Formula Iis generally given in one or more doses on a daily basis or from one tothree times a week.

[0102] The compound of the Formula I is administered by any conventionalmeans available for use in conjunction with pharmaceuticals, either asindividual therapeutic agents or in combination with other therapeuticagents.

[0103] A dosage unit may comprise a single compound or mixtures thereofwith other anti-cancer compounds, other cancer or tumor growthinhibiting compounds. The compound of the Formula I can be administeredin oral dosage forms as tablets, capsules, pills, powders, granules,elixirs, tinctures, suspensions, syrups, and emulsions. The compound ofthe Formula I may also be administered in intravenous (bolus orinfusion), intraperitoneal, subcutaneous, or intramuscular form, allusing dosage forms well known to those of ordinary skill in thepharmaceutical arts.

[0104] The compound of the Formula I is typically administered inadmixture with suitable pharmaceutical diluents, extenders, excipients,or carriers (collectively referred to herein as a pharmaceuticallyacceptable carrier or carrier materials) suitably selected with respectto the intended form of administration and as consistent withconventional pharmaceutical practices. The unit will be in a formsuitable for oral, rectal, topical, intravenous injection or parenteraladministration.

[0105] The compound of the Formula I can be administered alone but isgenerally mixed with a pharmaceutically acceptable carrier. This carriercan be a solid or liquid, and the type of carrier is generally chosenbased on the type of administration being used.

[0106] Specific examples of pharmaceutical acceptable carriers andexcipients that may be used to formulate oral dosage forms of thepresent invention are described in U.S. Pat. No. 3,903,297 to Robert,issued Sep. 2, 1975. Techniques and compositions for making dosage formsuseful in the present invention are described in the followingreferences: 7 Modern Pharmaceutics, Chapters 9 and 10 (Banker & Rhodes,Editors, 1979); Pharmaceutical Dosage Forms: Tablets (Lieberman et al.,1981); Ansel, Introduction to Pharmaceutical Dosage Forms 2nd Edition(1976): Remington's Pharmaceutical Sciences, 17th ed. (Mack PublishingCompany. Easton, Pa., 1985); Advances in Pharmaceutical Sciences (DavidGanderton, Trevor Jones. Eds., 1992); Advances in PharmaceuticalSciences Vol 7. (David Ganderton. Trevor Jones. James McGinity, Eds.,1995); Aqueous Polymeric Coatings for Pharmaceutical Dosage Forms (Drugsand the Pharmaceutical Sciences, Series 36 (James McGinity,, Ed.. 1989);Pharmaceutical Particulate Carriers: Therapeutic Applications: Drugs andthe Pharmaceutical Sciences, Vol 61 (Alain Rolland, Ed., 1993); DrugDeliver) to the Gastrointestinal Tract (Ellis Horwood Books in theBiological Sciences. Series in Pharmaceutical Technology; J. G. Hardy,S. S. Davis, Clive G. Wilson, Eds.); Modern Pharmaceutics Drugs and thePharmaceutical Sciences, Vol 40 (Gilbert S. Banker, Christopher T.Rhodes, Eds.), the disclosures of which are hereby incorporated byreference.

[0107] Tablets may contain suitable binders, lubricants, disintegratingagents, coloring agents, flavoring agents, flow-inducing agents, andmelting agents. For instance, for oral administration in the dosage unitform of a tablet or capsule, the active drug component can be combinedwith an oral, non-toxic, pharmaceutically acceptable, inert carrier suchas lactose, gelatin, agar, starch, sucrose, glucose, methyl cellulose,magnesium stearate, dicalcium phosphate, calcium sulfate, mannitol,sorbitol and the like.

[0108] Suitable binders include starch, gelatin, natural sugars such asglucose or beta-lactose, corn sweeteners, natural and synthetic gumssuch as acacia, tragacanth, or sodium alginate, carboxymethylcellulose,polyethylene glycol, waxes, and the like. Lubricants used in thesedosage forms include sodium oleate, sodium stearate, magnesium stearate,sodium benzoate, sodium acetate, sodium chloride, and the like.Disintegrators include, without limitation, starch, methyl cellulose,agar, bentonite, xanthan gum, and the like.

[0109] The compound of the Formula I can also be administered in theform of liposome delivery systems, such as small unilamellar vesicles,large unilamallar vesicles, and multilamellar vesicles. Liposomes can beformed from a variety of phospholipids, such as cholesterol,stearylamine, or phosphatidylcholines.

[0110] The compound of the Formula I may also be coupled to solublepolymers as targetable drug carriers or as a prodrug. Such polymersinclude polyvinylpyrolidone. pyran copolymer,polyhydroxylpropylmethacrylamide-phenol,polyhydroxyethylaspartamidephenol, or polyethyleneoxide-polylysinesubstituted with palmitoyl residues. Furthermore, the compound of theFormula I may be coupled to a class of biodegradable polymers useful inachieving controlled release of a drug, for example, polylactic acid,polyglycolic acid, copolymers of polylactic and polyglycolic acid,polyepsilon caprolactone, polyhydroxy butyric acid, polyorthoesters,polyacetals, polydihydropyrans, polycyanoacylates, and crosslinked oramphipathic block copolymers of hydrogels.

[0111] The active ingredient can be administered orally in solid dosageforms, such as capsules, tablets, and powders, or in liquid dosageforms, such as elixirs, syrups, and suspensions. It can also beadministered parentally, in sterile liquid dosage forms.

[0112] Gelatin capsules may contain the active ingredient and powderedcarriers, such as lactose, starch, cellulose derivatives, magnesiumstearate, stearic acid, and the like. Similar diluents can be used tomake compressed tablets. Both tablets and capsules can be manufacturedas immediate release products or as sustained release products toprovide for continuous release of medication over a period of hours.Compressed tablets can be sugar coated or film coated to mask anyunpleasant taste and protect the tablet from the atmosphere, or entericcoated for selective disintegration in the gastrointestinal tract.

[0113] For oral administration in liquid dosage form, the oral drugcomponents are combined with any oral, non-toxic, pharmaceuticallyacceptable inert carrier such as ethanol, glycerol, water, and the like.Examples of suitable liquid dosage forms include solutions orsuspensions in water, pharmaceutically acceptable fats and oils,alcohols or other organic solvents, including esters, emulsions, syrupsor elixirs, suspensions, solutions and/or suspensions reconstituted fromnon-effervescent granules and effervescent preparations reconstitutedfrom effervescent granules. Such liquid dosage forms may contain, forexample, suitable solvents, preservatives, emulsifying agents,suspending agents, diluents, sweeteners, thickeners, and melting agents.

[0114] Liquid dosage forms for oral administration can contain coloringand flavoring to increase patient acceptance. In general, water, asuitable oil, saline, aqueous dextrose (glucose), and related sugarsolutions and glycols such as propylene glycol or polyethylene glycolsare suitable carriers for parenteral solutions. Solutions for parenteraladministration preferably contain a water soluble salt of the activeingredient. suitable stabilizing agents, and if necessary, buffersubstances. Antioxidizing agents such as sodium bisulfite, sodiumsulfite, or ascorbic acid, either alone or combined, are suitablestabilizing agents. Also used are citric acid and its salts and sodiumEDTA. In addition, parenteral solutions can contain preservatives, suchas benzalkonium chloride, methyl- or propyl-paraben, and chlorobutanol.Suitable pharmaceutical carriers are described in Remington'sPharmaceutical Sciences, Mack Publishing Company, a standard referencetext in this field.

[0115] The compound of the Formula I may also be administered inintranasal form via use of suitable intranasal vehicles, or viatransdermal routes, using those forms of transdermal skin patches wellknown to those of ordinary skill in that art. To be administered in theform of a transdermal delivery system, the dosage administration willgenerally be continuous rather than intermittant throughout the dosageregimen.

[0116] Parenteral and intravenous forms may also include minerals andother materials to make them compatible with the type of injection ordelivery system chosen.

[0117] Useful pharmaceutical dosage forms for administration of thecompound of the Formula I are illustrated as follows:

Capsules

[0118] A large number of unit capsules are prepared by filling standardtwo-piece hard gelatin capsules each with 100 to 500 milligrams ofpowdered active ingredient, 5 - 150 milligrams of lactose, 5 -50milligrams of cellulose, and 6 milligrams magnesium stearate.

Soft Gelatin Capsules

[0119] A mixture of active ingredient in a digestible oil such assoybean oil, cottonseed oil or olive oil is prepared and injected bymeans of a positive displacement pump into gelatin to form soft gelatincapsules containing 100 - 500 milligrams of the active ingredient. Thecapsules are washed and dried.

Tablets

[0120] A large number of tablets are prepared by conventional proceduresso that the dosage unit was 100 - 500 milligrams of active ingredient.0.2 milligrams of colloidal silicon dioxide, 5 milligrams of magnesiumstearate, 50-275 milligrams of microcrystalline cellulose, 11 milligramsof starch and 98.8 milligrams of lactose Appropriate coatings may beapplied to increase palatability or delay absorption.

Injectable solution

[0121] A parenteral composition suitable for administration by injectionis prepared by stirring 1.5% by weight of active ingredient in 10% byvolume propylene glycol and water. The solution is made isotonic withsodium chloride and sterilized.

Suspension

[0122] An aqueous suspension is prepared for oral administration so thateach 5 ml contain 100 mg of finely divided active ingredient, 200 mg ofsodium carboxymethyl cellulose, 5 mg of sodium benzoate, 1.0 g ofsorbitol solution, U.S.P., and 0.025 ml of vanillin.

[0123] The present invention also includes pharmaceutical kits useful,for example, for the treatment of cancer, which comprise one or morecontainers containing a pharmaceutical composition comprising atherapeutically effective amount of the compound of the Formula I. Suchkits may further include, if desired, one or more of variousconventional pharmaceutical kit components, such as, for example,containers with one or more pharmaceutically acceptable carriers,additional containers, etc., as will be readily apparent to thoseskilled in the art. Printed instructions, either as inserts or aslabels, indicating quantities of the components to be administered,guidelines for administration, and/or guidelines for mixing thecomponents, may also be included in the kit. It should be understoodthat although the specified materials and conditions are important inpracticing the invention, unspecified materials and conditions are notexcluded so long as they do not prevent the benefits of the inventionfrom being realized.

[0124] The chemotherapeutic agents, the compound of the Formula I and,optionally, the potentiators are typically mixed with a pharmaceuticallyacceptable carrier. This carrier can be a solid or liquid and the typeis generally chosen based on the type of administration being used. Theactive agent can be coadministered in the form of a tablet or capsule,liposome, as an agglomerated powder or in a liquid form. Examples ofsuitable solid carriers include lactose, sucrose, gelatin and agar.Capsule or tablets can be easily formulated and can be made easy toswallow or chew; other solid forms include granules, and bulk powders.Tablets may contain suitable binders, lubricants, diluents,disintegrating agents, coloring agents, flavoring agents, flow-inducingagents, and melting agents. Examples of suitable liquid dosage formsinclude solutions or suspensions in water, pharmaceutically acceptablefats and oils, alcohols or other organic solvents, including esters,emulsions, syrups or elixirs, suspensions, solutions and/or suspensionsreconstituted from non-effervescent granules and effervescentpreparations reconstituted from effervescent granules. Such liquiddosage forms may contain, for example, suitable solvents, preservatives,emulsifying agents, suspending agents, diluents, sweeteners, thickeners,and melting agents. Oral dosage forms optionally contain flavorants andcoloring agents. Parenteral and intravenous forms would also includeminerals and other materials to make them compatible with the type ofinjection or delivery system chosen.

[0125] The compound of the Formula I is generally safe. The LD₅₀ is50,000 mg/kg when given orally in a mouse. There are generally nospecial handling requirements. The compound of the Formula I can begiven orally, and as it is not very water soluble, it is preferablygiven in tablet form or as a suspension.

[0126] D. METHOD OF TREATMENT

[0127] The method of treatment can be any suitable method which iseffective in the treatment of the particular cancer or tumor type beingtreated. Treatment may be oral, rectal, topical, parenteral orintravenous administration or by injection into the tumor or cancer. Themethod of applying an effective amount also varies depending on thedisorder being treated. It is believed that parenteral treatment byintravenous, subcutaneous, or intramuscular application of the thecompound of the Formula I, formulated with an appropriate carrier,additional cancer inhibiting compound or compounds or diluent tofacilitate application will be the preferred method of administering thecompounds to warm blooded animals.

[0128] In addition to the use of chemotherapeutic agents andpotentiators, the compound of the Formula I can be combined with othertherapeutic agents. Preferred adjuvants include griseofulvin,fluoconazole, glyphosate and propicodazole. The dosage level of thesecompounds when used in conjunction with the compound of the Formula Iwill be from about 150 mg/kg to about 6000 mg/kg.

[0129] The following examples illustrate the utility of the compound ofthe Formula I as an anti-leukemia agent.

EXAMPLE 1 Carbendazim in a P388 in vivo study

[0130] Mice were randomly selected and divided into five groups of tenmice each: Group 1—a control group receiving canola oil but no drugtreatment; Group 2—a treatment group receiving 125 mg of cytoxan(2-[bis(2-chloroethyl)-amino-1-oxo-2-aza-5-oxophosphoridin) per kg ofbody weight; Group 3—a treatment group receiving 4000 mg of carbendazimper kg of body weight; Group 4—a treatment group receiving 2500 mg ofcarbendazim per kg of body weight; and Group 5—a treatment groupreceiving 1000 mg of carbendazim per kg of body weight. The five groupswere infected with leukemia [P338]. The diseased animals were dosed forfive days, off two days, dosed again for another five days and off againfor three days. Even with this irregular dosing regimen, positiveresults were noted. Of the ten mice in Group 1, one died after eightdays, eight died after ten days, and all ten were dead after eleven daysafter infection with leukemia. Of the ten mice in Group 2, none died upto twenty one days after infection with leukemia. Of the ten mice inGroup 3, one died on day fourteen, two each died on days 15, 16 and 17and one each died on days 20, 21, and 22 after infection with leukemia.The mean number of survival days is 17.3 for Group 3. Of the ten mice inGroup 4, two died on day fourteen, four died on day 15, 1 on day 16, 2on day 19 and one on day 21 after infection with leukemia. The meannumber of survival days is 16.5 for Group 4. Of the ten mice in Group 5,two each died on days 12, 13, 14, and 15, and one each died on days 16and 17 after infection with leukemia. The mean number of survival daysis 14.1 for Group 5.

[0131] Accordingly, carbendazim, a compound of the Formula I, iseffective at extending the life span of a mammal having leukemia.

EXAMPLE 2 Carbendazim (A compound of the Formula I) In CombinationGriseofulvin

[0132] In an in vivo mouse study for leukemia (P3SS), carbendazim(2-carbonylaminobenzimidazole) was tested in combination withgriseofulvin. Cytoxan was the positive control at 300 mg/kg (qdxl) andhad no deaths during the test period. The results are tabulated below: %increase in survival time Dose mg/kg dose mg/kg versus nontreatedGriseofulvin carbendazim control 0 3000 176 3000 3000  93 4000 3000 05000 3000 0 0 2000 190 3000 2000 186 4000 2000 157 5000 2000 0 0 1000153 3000 1000 187 4000 1000 183 5000 1000 166 0 0 100 (control) 3000 0130 4000 0 165 5000 0 213

[0133] Accordingly, griseofulvin in combination with carbendazim isuseful in extending the life span of a warm-blooded mammal havingleukemia. Further, a composition comprising therapeutically effectiveamounts of carbendazim, a compound of the Formula I, and griseofulvin isuseful for the treatment of leukemia in warm-blooded mammals andespecially for extending the life span of warm-blooded mammals havingleukemia. For example, when the combination of carbendazim andgriseofulvin is administered at a total of 5,000 mg/kg or less, thesurvival rate of mice having leukemia is increased. As a furtherexample, when the ratio of griseofulvin to carbendazim is 5 to 1 orless, the survival time of mice having leukemia is increased.

EXAMPLE 3 Determining if a Leukemia is Susceptible to Treatment

[0134] This example describes a general method for determining whetheror not a particular type of leukemia is susceptible to treatment. Bloodor bone marrow containing leukemic cells is obtained from a mammal anddivided into two aliquots: a first control aliquot and a second testaliquot. An initial count of the leukemic cells is taken. The leukemiccells, which have been isolated and resuspended in a solution or whichare present in the sampled blood, are exposed to a sufficient amount ofthe compound of the Formula I (usually 0.01 mg - 10 mg/mL of solution)for a sufficient period of time(usually 8-72 hours) to inhibit thegrowth of, inhibit the proliferation of or lyse the leukemic cells. Thecontrol aliquot is not exposed to the compound of the Formula I. A finalcount of the leukemic cells in each aliquot is taken and compared. Asolution containing leukemia that is susceptible to treatment with acompound of the Formula I will have a lower leukemic cell count aftertreatment than does the control aliquot.

What is claimed is:
 1. A method of treating leukemia susceptible totreatment in an animal comprising the step of administering to theanimal a pharmaceutically acceptable carrier and a safe and effectiveamount of a compound of the Formula I

or a pharmaceutically acceptable salt or prodrug form thereof, wherein:X is hydrogen, halogen or alkyl of less than 7 carbon atoms; n is apositive integer of less than 4; Y is hydrogen, chlorine, nitro, methylor ethyl; R is hydrogen or an alkyl group of from 1 to 8 carbon atoms,alkylcarbamyl; R₂ is 4-thiazolyl or NHCOOR₁; and R₁ is an aliphatichydrocarbon of less than 7 carbon atoms.
 2. A method of inhibiting theproliferation of leukemic cells in vitro, in vivo or ex vivo comprisingthe step of treating said cells with an effective amount of the compoundof the Formula I,

or a pharmaceutically acceptable salt or prodrug form thereof, wherein:X is hydrogen, halogen or alkyl of less than 7 carbon atoms; n is apositive integer of less than 4; Y is hydrogen, chlorine, nitro, methylor ethyl; R is hydrogen or an alkyl group of from 1 to 8 carbon atoms;R₂ is 4-thiazolyl or NHCOOR₁; and R₁ is an aliphatic hydrocarbon of lessthan 7 carbon atoms.
 3. A method of inhibiting the growth of leukemiccells in vitro, in vivo or ex vivo comprising the step of treating saidcells with an effective amount of the compound of the Formula I,

or a pharmaceutically acceptable salt or prodrug form thereof, wherein:X is hydrogen, halogen or alkyl of less than 7 carbon atoms; n is apositive integer of less than 4; Y is hydrogen, chlorine, nitro, methylor ethyl; R is hydrogen or an alkyl group of from 1 to 8 carbon atoms;R₂ is 4-thiazolyl or NHCOOR₁; and R₁ is an aliphatic hydrocarbon of lessthan 7 carbon atoms.
 4. A method of extending the life span of an animalhaving leukemia comprising the step of administering to the animal aneffective amount of the compound of the Formula I,

or a pharmaceutically acceptable salt or prodrug form thereof, wherein:X is hydrogen, halogen or alkyl of less than 7 carbon atoms; n is apositive integer of less than 4; Y is hydrogen, chlorine, nitro, methylor ethyl; R is hydrogen or an alkyl group of from 1 to 8 carbon atoms;R₂ is 4-thiazolyl or NHCOOR₁; and R₁ is an aliphatic hydrocarbon of lessthan 7 carbon atoms; whereby the life span of the animal is extendedbeyond the expected life span of a comparable animal having a comparabledegree of leukemia development not being treated with a compound of theFormula I.
 5. A method according to claim 1 , wherein R₁ is an alkylgroup of less than 7 carbon atoms
 6. A method according to claim 2 ,wherein R₁ is an alkyl group of less than 7 carbon atoms.
 7. A methodaccording to claim 3 , wherein R₁ is an alkyl group of less than 7carbon atoms.
 8. A method according to claim 4 , wherein R₁ is an alkylgroup of less than 7 carbon atoms.
 9. A method according to claim 1 ,wherein R is an alkyl of from 1 to 8 carbon atoms, and R₁ is methyl,ethyl or isopropyl.
 10. A method according to claim 2 , wherein R is analkyl of from 1 to 8 carbon atoms, and R₁ is methyl, ethyl or isopropyl.11. A method according to claim 3 , wherein R is an alkyl of from 1 to 8carbon atoms, and R₁ is methyl, ethyl or isopropyl.
 12. A methodaccording to claim 4 , wherein R is an alkyl of from 1 to 8 carbonatoms, and R₁ is methyl, ethyl or isopropyl.
 13. A method according toclaim 1 , wherein Y is chloro and X is hydrogen.
 14. A method accordingto claim 1 , wherein the compound of the Formula I is selected from thegroup consisting of 2-(4-thiazolyl)benzimidazole and2-(methoxycarbonylamino)benzimidzole.
 15. A method according to claim 2, wherein the compound of the Formula I is selected from the groupconsisting of 2-(4-thiazolyl)benzimidazole and2-(methoxycarbonylamino)benzimidzole.
 16. A method according to claim 3, wherein the compound of the Formula I is selected from the groupconsisting of 2-(4-thiazolyl)benzimidazole and2-(methoxycarbonylamino)benzimidzole.
 17. A method according to claim 4, wherein the compound of the Formula I is selected from the groupconsisting of 2-(4-thiazolyl)benzimidazole and2-(methoxycarbonylamino)benzimidzole.
 18. A method according to claim 1, further comprising the step of administering to said animal aneffective amount of one or more of a potentiator or a chemotherapeuticagent.
 19. A method according to claim 2 , further comprising the stepof administering to said animal an effective amount of one or more of apotentiator or a chemotherapeutic agent.
 20. A method according to claim18 , wherein said potentiator is selected from the group consisting ofprocodazole; triprolidine; macrophage colony-stimulating factor (M-CSF);7-thia-8-oxoguanosine; 6-mercaptopurine and vitamin A (retinol).
 21. Amethod according to claim 18 , wherein said chemotherapeutic agent isselected from the group consisting of a-interferon; interleukin-2;cytarabine and mitoxantrone; cytarabine and daunorubicin and6-thioguanine; cyclophosphamide and 2-chloro-2′-deoxyadenosine; VP-16and cytarabine and idorubicin or mitoxantrone; fludarabine andcytarabine and g-CSF; chlorambucil; cyclophosphamide and vincristine and(prednisolone or prednisone) and optionally doxorubicin; tyrosine kinaseinhibitor; an antibody; glutamine; clofibric acid; all-trans retinoicacid; ginseng diyne analog; KRN8602 (anthracycline drug); temozolomideand poly(ADP-ribose) polymerase inhibitors; lysofylline; cytosinearabinoside; chlythorax and elemental enteral diet enriched withmedium-chain triglycerides; amifostine; gilvusmycin; and a hot waterextract of the bark of Acer nikoense.
 22. A method according to claim 3, further comprising the step of treating said cells with an effectiveamount of one or more of a potentiator or a chemotherapeutic agent. 23.A method according to claim 22 , wherein said potentiator is selectedfrom the group consisting of procodazole; triprolidine; macrophagecolony-stimulating factor (M-CSF); 7-thia-8-oxoguanosine;6-mercaptopurine and vitamin A (retinol).
 24. A method according toclaim 22 , wherein said chemotherapeutic agent is selected from thegroup consisting of a-interferon; interleukin-2; cytarabine andmitoxantrone; cytarabine and daunorubicin and 6-thioguanine;cyclophosphamide and 2-chloro-2′-deoxyadenosine; VP-16 and cytarabineand idorubicin or mitoxantrone; fludarabine and cytarabine and g-CSF;chlorambucil; cyclophosphamide and vincristine and (prednisolone orprednisone) and optionally doxorubicin; tyrosine kinase inhibitor; anantibody; glutamine; clofibric acid; all-trans retinoic acid; ginsengdiyne analog; KRN8602 (anthracycline drug); temozolomide andpoly(ADP-ribose) polymerase inhibitors; lysofylline; cytosinearabinoside; chlythorax and elemental enteral diet to enriched withmedium-chain triglycerides; amifostine; gilvusmycin; and a hot waterextract of the bark of Acer nikoense.